Specifying priority on a virtual station interface discovery and configuration protocol response

ABSTRACT

A method implemented by a network component is provided. The method includes receiving a Virtual Station Interface (VSI) Discovery Protocol (VDP) request from an Edge Virtual Bridging (EVB) station and transmitting, to the EVB station, a VDP Response in response to the request. The VDP Response includes a VDP Type-Length-Value (TLV) having a Filter Information field. The Filter Information field is configured to specify a Priority Code Point (PCP) value associated with one or more Virtual Local Area Network (VLAN) Identifier (VID) values carried by the VDP Response. The PCP value is carried in a PCP field and adopted by the EVB station as a default PCP value associated with the VSI and at least one VID. The Filter Information field further contains a PCP Significant (PS) field associated with each PCP field, and wherein the PS field indicates whether the PCP field carries the PCP value.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/229,374 filed Sep. 9, 2011 by Robert Sultan, et al. andentitled “Specifying Priority on a Virtual Station Interface Discoveryand Configuration Protocol Response,” which claims the benefit of U.S.Provisional Patent Application No. 61/381,808 filed Sep. 10, 2010 byYizhou Li, et al. and entitled “Method to Pass Virtual Local AreaNetwork Information in Virtual Station Interface Discovery andConfiguration Protocol,” and U.S. Provisional Patent Application No.61/430,837 filed Jan. 7, 2011 by Robert Sultan, et al. and entitled“Specifying Priority on a Virtual Server Interface Discovery ProtocolResponse,” all of which are incorporated herein by reference as ifreproduced in their entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

BACKGROUND

Modern communication and data networks, such as Ethernet based networks,are comprised of nodes that transport data through the network. Thenodes may include switches, and/or bridges that transport the individualdata frames through the network. For example, the Institute ofElectrical and Electronics Engineers (IEEE) 802.1Q compliant Ethernetbridges forward data frames based on a medium access control (MAC)address and virtual local area network identifier (VID) contained in theheader of the frame. Frames may be granted priority in forwardingrelative to other frames according to the value of a Priority Code Point(PCP) value also contained within the header of the frame.

SUMMARY

In one embodiment, the disclosure includes method implemented by anetwork component is provided. The method includes receiving a VirtualStation Interface (VSI) Discovery Protocol (VDP) request from an EdgeVirtual Bridging (EVB) station and transmitting, to the EVB station, aVDP Response in response to the request. The VDP Response includes a VDPType-Length-Value (TLV) having a Filter Information field. The FilterInformation field is configured to specify a (Priority Code Point) PCPvalue associated with one or more Virtual Local Area Network (VLAN)Identifier (VID) values carried by the VDP Response. The PCP value iscarried in a PCP field and adopted by the EVB station as a default PCPvalue associated with the VSI and at least one VID. The FilterInformation field further contains a PCP Significant (PS) fieldassociated with each PCP field, and wherein the PS field indicateswhether the PCP field carries the PCP value.

In another embodiment, the disclosure includes a networking component.The network component includes a transmitter configured to send to anEdge Virtual Bridging (EVB) bridge a virtual station interface (VSI)discovery and configuration protocol (VDP) request, a receiverconfigured to receive a VDP response from the EVB bridge in response tothe VDP request, wherein the VDP response includes a VDPType-Length-Value (TLV) having a Filter Information field, and theFilter Information field is configured to specify a PCP value associatedwith one or more Virtual Local Area Network (VLAN) Identifier (VID)values carried by the VDP Response; wherein the PCP value is carried ina PCP field and adopted by the networking component as a default PCPvalue associated with the VSI and at least one VID, wherein the FilterInformation field further contains a PCP Significant (PS) fieldassociated with each PCP field, and wherein the PS field indicateswhether the PCP field carries the PCP value, and a logic unit coupled tothe transmitter and the receiver, wherein the logic unit is configuredto adopt the PCP value as a default PCP value associated with the VSIand at least one VID.

In yet another embodiment, the disclosure includes a method implementedby at least one network component. The method includes sending from avirtual station to an Edge Virtual Bridging (EVB) bridge a virtualstation interface (VSI) discovery and configuration protocol (VDP)request that comprises a first Priority Code Point (PCP) field and afirst PCP Significant (PS) field, receiving at the virtual station a VDPresponse from the EVB bridge, wherein the VDP associate responseincludes a second PCP field and a second PS field set to indicate adefault priority value, and adopting the default priority value to aVSI, wherein a plurality of MAC frames transported via the VSI comprisethe default priority value.

These and other features will be more clearly understood from thefollowing detailed description taken in conjunction with theaccompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this disclosure, reference is nowmade to the following brief description, taken in connection with theaccompanying drawings and detailed description, wherein like referencenumerals represent like parts.

FIG. 1 is a schematic diagram of an embodiment of a data center network.

FIG. 2 is a schematic diagram of an embodiment of a VDP TLV.

FIG. 3 is a protocol diagram of an embodiment of a method for getting aVDP priority indication.

FIG. 4 is a schematic diagram of an embodiment of a network unit.

FIG. 5 is a schematic diagram of an embodiment of a general-purposecomputer system.

DETAILED DESCRIPTION

It should be understood at the outset that although an illustrativeimplementation of one or more embodiments are provided below, thedisclosed systems and/or methods may be implemented using any number oftechniques, whether currently known or in existence. The disclosureshould in no way be limited to the illustrative implementations,drawings, and techniques illustrated below, including the exemplarydesigns and implementations illustrated and described herein, but may bemodified within the scope of the appended claims along with their fullscope of equivalents.

A data center may comprise a plurality of bridges that are coupled to aplurality of end-stations. The bridges directly attached to end-stationsmay deploy IEEE standard 802.1Qbg Edge Virtual Bridging (EVB). Suchbridges are known as EVB bridges. An EVB bridge is attached to aplurality of EVB stations, with each EVB station containing a pluralityof end-stations. End-stations may share channel or physical linkconnectivity to the EVB Bridge. In such cases, each end-station is saidto be connected to the EVB Bridge via a virtual station interface (VSI).IEEE 802.1Qbg EVB defines a VSI Discovery Protocol (VDP) message thatmay be exchanged by an EVB station and an EVB bridge, carryinginformation such as <MAC, VID> pair values that can be used to identifytraffic associated with a given VSI at the EVB bridge. IEEE standard802.1 Qbg EVB is published in a draft athttp://www.ieee802.org/1/files/private/bg-drafts/d1/802-1qbg-d1-6.pdf,which is incorporated herein by reference. The VDP is described inclause 41 of the draft. VDP supports control communication between anEVB station and an EVB bridge. The protocol supports the transmission ofa VDP Associate Request messages from EVB station to EVB bridge, thereception of the VDP Associate Request by the EVB bridge, thetransmission of a VDP response from EVB bridge to EVB station, and thereception of the VDP Associate Response by the EVB station. The purposeof VDP is to bind or unbind a VSI and associated properties with a portof the EVB bridge. Disclosed herein is a system and methods for using aVDP Associate Response message to communicate information related tosetting the PCP field value for MAC frames transmitted from an EVBstation towards a data center network coupled to the EVB station.

FIG. 1 illustrates an embodiment of a data center network 100. The datacenter network 100 may be configured to allow communications between aplurality of attached end-stations 104. The data center network 100 maycomprise a plurality of interconnected network bridges 102 conforming,for example to IEEE standard 802.1Q-2011 VLAN Bridging. Bridges at theedge of the data center network 100 may conform to IEEE standard802.1Qbg EVB and may be known as EVB bridges 106. A plurality ofend-stations may conform to IEEE standard 802.1Qbg EVB and may be knownas an EVB station 108.

An end-station 104 may communicate data traffic towards the EVB bridge106 via a VSI 110. An EVB station 108 may exchange control informationwith the EVB bridge 106 via a VDP, e.g., as described by IEEE standard802.1Qbg.

In some scenarios, the EVB station may need to determine a PCP valueassociated with MAC frames to be transmitted on a VSI. In suchscenarios, the EVB station and EVB bridge may exchange VDP association(request and response) messages to obtain the PCP value that is to becarried by frames transmitted on the VSI or to obtain information thatis used to derive such a value.

FIG. 2 illustrates an embodiment of a VDP TLV field 200, which may beused to obtain the PCP value at the EVB station. The VDP TLV 200 may bebased on the VDP TLV described in clause 41 of the IEEE 802.1Qbg EVBdraft 1.3 and further in subclause 41.1 with some additions or changes,as described below. The VDP TLV may be sent from the EVB bridge to theEVB station, (e.g., in response to a VDP associate request from the EVBstation) to communicate a PCP value. The VDP TLV field 200 maycorrespond to a MAC/VLANs field in the VDP TLV described in clause 41 ofthe IEEE 802.1Qbg draft 1.3. The VDP TLV field 200 may comprise a numberof entries field 202 and a MAC Address field 204. The VDP TLV field 200may also comprise a PCP/VID (PV) field 206 that may be about two octetslong. The PV field 206 may comprise a PCP Significant (PS) field 208(e.g., of about one bit in size), a PCP field 210 (e.g., of about threebits in size), and a VID field 212 (e.g., of about 12 bits in size). Thecombination of the PS field 208, PCP field 210, and VID field 212 mayalso be referred to herein as a Filter Info field, which may have aboutsixteen bits.

In subclause 41.1 of the IEEE 802.1Qbg draft for EVB, the VDP TLVcomprises a VID field of about 16 bits. The high-order four bits of thisVID field is reserved. Thus one bit of the reserved high-order four bitsmay be used for the PS field 208 and the remaining three bits may beused for the PCP field 210. The PS field 208 may be set (e.g., to one)in a response from the EVB bridge to the EVB station to indicate thatthe PCP field 210 is significant. If the PS field 208 is not set (e.g.,equal to zero), then the PCP field 210 is not significant. If the PCPfield 210 is significant, then the PCP field 210 in the response mayindicate a default priority value for an associated VSI that may beindicated in the VDP associate request/response. The MAC frames sent bythe end-station towards the network on that VSI may use the defaultpriority value. The server may use the obtained default PCP field valueto determine the PCP value associated with each MAC frame sent on a VSIusing an algorithm local to the end-station.

The PCP field 210 may be communicated in the direction from the EVBbridge to the EVB station. As such, the PS field 208 may be set to aboutzero in a VDP request message from the EVB station to the EVB bridge,and may be set to about one in a VDP message response from the EVBbridge to the EVB station if the corresponding PCP field 210 issignificant. The PV field 206 (including the PS field 208, PCP field210, and VID field 212) may be repeated a plurality of times (for aplurality of VIDs) equal to the value indicated in the number of thenumber of entries field 202. In the case where a plurality of MACAddress fields 204 and PV fields 206 are repeated in the VDP TLV field200, the PCP field 210 in the first or last PV field 206 may be used toindicate the default priority value for a VSI (at the EVB station).Alternatively, a plurality of significant PCP fields 210 in the repeatedPV fields 206 may indicate default priority values for a plurality ofcorresponding VID fields 212 in the repeated PV fields 206.

In an embodiment, the PS field 208 and the PCP field 210 may be setindependently in each of the repeated PV fields 206. Each PS field 208and corresponding PCP field 210 may be set according to the followingrules:

-   1. If the PS field 208 is ‘set’ for an entry, then the PCP field 210    may be applied only to traffic carrying the specified VID.-   2. The first entry for which the PS field 208 is ‘set’ may identify    the value of PCP to be applied to all traffic associated with the    VSI.-   3. The last entry for which the PS field 208 is ‘set’ may identify    the value of PCP to be applied to all traffic associated with the    VSI.-   4. All entries having the PCP field 208 set may specify the same    value of PCP or else an error may be detected.    Additional and/or alternative rules may also be applied to set the    PS field 208 and the PCP field 210.

In some embodiments, the PCP field 210 may specify a PCP value that maybe carried by the MAC frames from the EVB station on the VSI, or mayspecify a PCP value that may be carried by the MAC frames on the VSIthat are associated with a specified VID value. In other embodiments,the PCP field 210 may specify a value that may be combined and used withother information known to the EVB station to specify the PCP value thatmay be carried by the MAC frames. For instance, any combination of thefollowing items of information may be combined and used with the PCPfield 210 to determine the PCP:

-   1. The value of the PCP set by the user of the VM associated with    the VSI.-   2. The identity of the application associated with the MAC frame as    can be inferred by the hypervisor of the EVB station by examining,    for example, the port number specified at the transport layer (e.g.,    Transmission Control Protocol (TCP) or User Datagram Protocol (UDP)    port number).-   3. The priority value specified by the network-layer packet    associated with the MAC frame, for example, the IP precedence bits    (described in the Internet Engineering Task Force (IETF) Request for    Comments (RFC) 791).    Additional and/or alternative items of information may also be    combined with the PCP field 210.

In an embodiment, the PCP field 210 may identify a service class (SC).For example, the PCP values of ‘0’, ‘1’, and ‘2’ may represent bronze,silver, and gold service classes, respectively. For instance, the MACframes associated with an application, e.g., voice, may be assigned aPCP value of ‘0’ if the MAC frames carry voice traffic associated with aVSI that belongs to the bronze SC, a PCP value of ‘3’ if the MAC framescarry voice traffic associated with a VSI that belongs to the silver SC,and a PCP value of ‘7’ if the MAC frames carry voice traffic associatedwith a VSI that belongs to the gold SC. In an embodiment, the PS field208 in a VDP request message from the EVB station to the EVB bridge mayindicate whether or not the EVB station expects the EVB bridge toprovide a significant PCP field 210 and value in a VDP response message.

In some embodiments, the VDP response message may comprise both a PCPvalue and a SC value. The SC value may be used to compute a second PCPvalue, which may not be greater than the PCP value specified in the VDPresponse message. Providing two items of information in the VDP responsemessage may require a different encoding in the VDP response message asdescribed above. For instance, a plurality of fields may be used beforethe VDP TLV field 200 in the VDP message to provide multiple items ofinformation. The VDP message may comprise a SC Significant (SCS) field(e.g., of about one bit in size), a SC field (e.g., of about eight bitsin size), a PCP Significant (PCPS) field (e.g., of about one bit insize), and a PCP field (e.g., of about eight bits in size). The SCSfield and SC field may precede the VDP TLV field 200 that comprises PCPSfield (PS field 208) and PCP field (PCP field 210). In any of theembodiments above, the network or EVB bridge may use a VSI Typedatabase, also referred to as a port profile database, to maintain oneor more PCP values that are communicated from the EVB bridge to the EVBstation.

FIG. 3 illustrates an embodiment of a method 300 for getting a VDPpriority indication. The method 300 may allow an EVB station 310 torequest from a network via an EVB bridge 320 a priority value for MACtraffic bound to a VSI and allow the EVB bridge 320 to provide thepriority value in a response. At step 302, the EVB station 310 may senda VDP Associate Request message to the EVB bridge 320 to obtain apriority value for traffic (MAC frames) transported via a VSI at the EVBstation 310. The VDP Associate Request message may comprise VSI Type(VTID) and VSI ID (VSIID) information, such as in a VDP TLV 200. At step304, the EVB bridge 320 may return a VDP Associate Response message tothe EVB station 310 of a priority value, e.g., a PCP and/or SC value,for the indicated VSI and/or VID in the VDP Associate Request message.The VDP Associate Response message may comprise a result that indicateswhether the request was successfully met, a PS value (e.g., in a PSfield 208), and a PCP value (e.g., in a PCP field 210). The VDPAssociate Response message may carry a default PCP value in a PCP fieldand an indication as to whether the default PCP field is significant andmay be used by the EVB station 310.

FIG. 4 illustrates an embodiment of a network unit 400, which may be anydevice that transports and processes data through a network, e.g., thedata center network 100. For instance, the network unit may correspondto or may be located at the EVB station 108 or the EVB bridge 106. Thenetwork unit 400 may comprise one or more ingress ports or units 410coupled to a receiver (Rx) 412 for receiving signals and frames/datafrom other network components. The network unit 400 may comprise a logicunit 420 to determine which network components to send data to. Thelogic unit 420 may be implemented using hardware, software, or both. Thenetwork unit 400 may also comprise one or more egress ports or units 430coupled to a transmitter (Tx) 432 for transmitting signals andframes/data to the other network components. The receiver 412, logicunit 420, and transmitter 432 may also implement or support the method300 above. The components of the network unit 400 may be arranged asshown in FIG. 4.

The network components described above may be implemented on anygeneral-purpose network component, such as a computer or networkcomponent with sufficient processing power, memory resources, andnetwork throughput capability to handle the necessary workload placedupon it. FIG. 5 illustrates a typical, general-purpose network component500 suitable for implementing one or more embodiments of the componentsdisclosed herein. The network component 500 includes a processor 502(which may be referred to as a central processor unit or CPU) that is incommunication with memory devices including secondary storage 504, readonly memory (ROM) 506, RAM 508, input/output (I/O) devices 510, andnetwork connectivity devices 512. The processor 502 may be implementedas one or more CPU chips, or may be part of one or more applicationspecific integrated circuits (ASICs).

The secondary storage 504 is typically comprised of one or more diskdrives or tape drives and is used for non-volatile storage of data andas an over-flow data storage device if RAM 508 is not large enough tohold all working data. Secondary storage 504 may be used to storeprograms that are loaded into RAM 508 when such programs are selectedfor execution. The ROM 506 is used to store instructions and perhapsdata that are read during program execution. ROM 506 is a non-volatilememory device that typically has a small memory capacity relative to thelarger memory capacity of secondary storage 504. The RAM 508 is used tostore volatile data and perhaps to store instructions. Access to bothROM 506 and RAM 508 is typically faster than to second storage 504.

At least one embodiment is disclosed and variations, combinations,and/or modifications of the embodiment(s) and/or features of theembodiment(s) made by a person having ordinary skill in the art arewithin the scope of the disclosure. Alternative embodiments that resultfrom combining, integrating, and/or omitting features of theembodiment(s) are also within the scope of the disclosure. Wherenumerical ranges or limitations are expressly stated, such expressranges or limitations should be understood to include iterative rangesor limitations of like magnitude falling within the expressly statedranges or limitations (e.g., from about 1 to about 6 includes, 2, 3, 4,etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example,whenever a numerical range with a lower limit, R_(l), and an upperlimit, R_(u), is disclosed, any number falling within the range isspecifically disclosed. In particular, the following numbers within therange are specifically disclosed: R=R_(l)+k*(R_(u)−R_(l)), wherein k isa variable ranging from 1 percent to 60 percent with a 1 percentincrement, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 7percent, . . . , 70 percent, 71 percent, 72 percent, . . . , 97 percent,96 percent, 97 percent, 98 percent, 99 percent, or 60 percent. Moreover,any numerical range defined by two R numbers as defined in the above isalso specifically disclosed. Use of the term “optionally” with respectto any element of a claim means that the element is required, oralternatively, the element is not required, both alternatives beingwithin the scope of the claim. Use of broader terms such as comprises,includes, and having should be understood to provide support fornarrower terms such as consisting of, consisting essentially of, andcomprised substantially of. Accordingly, the scope of protection is notlimited by the description set out above but is defined by the claimsthat follow, that scope including all equivalents of the subject matterof the claims. Each and every claim is incorporated as furtherdisclosure into the specification and the claims are embodiment(s) ofthe present disclosure. The discussion of a reference in the disclosureis not an admission that it is prior art, especially any reference thathas a publication date after the priority date of this application. Thedisclosure of all patents, patent applications, and publications citedin the disclosure are hereby incorporated by reference, to the extentthat they provide exemplary, procedural, or other details supplementaryto the disclosure.

While several embodiments have been provided in the present disclosure,it should be understood that the disclosed systems and methods might beembodied in many other specific forms without departing from the spiritor scope of the present disclosure. The present examples are to beconsidered as illustrative and not restrictive, and the intention is notto be limited to the details given herein. For example, the variouselements or components may be combined or integrated in another systemor certain features may be omitted, or not implemented.

In addition, techniques, systems, subsystems, and methods described andillustrated in the various embodiments as discrete or separate may becombined or integrated with other systems, modules, techniques, ormethods without departing from the scope of the present disclosure.Other items shown or discussed as coupled or directly coupled orcommunicating with each other may be indirectly coupled or communicatingthrough some interface, device, or intermediate component whetherelectrically, mechanically, or otherwise. Other examples of changes,substitutions, and alterations are ascertainable by one skilled in theart and could be made without departing from the spirit and scopedisclosed herein.

What is claimed is:
 1. A method implemented by a network component,comprising: receiving a Virtual Station Interface (VSI) DiscoveryProtocol (VDP) request from an Edge Virtual Bridging (EVB) station;transmitting, to the EVB station, a VDP Response in response to therequest, wherein the VDP Response includes a VDP Type-Length-Value (TLV)having a Filter Information field, wherein the Filter Information fieldis configured to specify a Priority Code Point (PCP) value associatedwith one or more Virtual Local Area Network (VLAN) Identifier (VID)values carried by the VDP Response; wherein the PCP value is carried ina PCP field and adopted by the EVB station as a default PCP valueassociated with the VSI and at least one VID; and wherein the FilterInformation field further contains a PCP Significant (PS) fieldassociated with each PCP field, and wherein the PS field indicateswhether the PCP field carries the PCP value.
 2. The method of claim 1,wherein the PCP value is adopted by the EVB station as the default PCPvalue when the PCP field carries the PCP value.
 3. The method of claim1, further comprising sending data frames associated with the VSI andthe at least one VID to permit the EVB station to determine the PCPvalue associated with each data frame using an algorithm local to theEVB station.
 4. The method of claim 1, further comprising basing the PCPvalue on an identity of an application associated with a data frame asdetermined by an examination of higher layer information.
 5. The methodof claim 3, wherein the PCP field is assigned the default PCP value whenthe algorithm does not provide a specific PCP value for any given frame.6. The method of claim 1, wherein the PCP value is three bits in size,wherein the PS field is one bit in size, and wherein the PCP value isspecified when the PS field is set.
 7. The method of claim 6, whereinthe PCP value is used by the EVB station as the default PCP value whenthe PS field is set.
 8. The method of claim 1, wherein the PCP fieldcarries the PCP value when the PS field has a value of one, and whereinthe PCP field does not carry the PCP value when the PS field has a valueof zero.
 9. A networking component comprising: a transmitter configuredto send to an Edge Virtual Bridging (EVB) bridge a virtual stationinterface (VSI) discovery and configuration protocol (VDP) request; areceiver configured to receive a VDP response from the EVB bridge inresponse to the VDP request; wherein the VDP response includes a VDPType-Length-Value (TLV) having a Filter Information field, and theFilter Information field is configured to specify a Priority Code Point(PCP) value associated with one or more Virtual Local Area Network(VLAN) Identifier (VID) values carried by the VDP Response; wherein thePCP value is carried in a PCP field and adopted by the networkingcomponent as a default PCP value associated with the VSI and at leastone VID, wherein the Filter Information field further contains a PCPSignificant (PS) field associated with each PCP field, and wherein thePS field indicates whether the PCP field carries the PCP value; and alogic unit coupled to the transmitter and the receiver, wherein thelogic unit is configured to adopt the PCP value as a default PCP valueassociated with the VSI and at least one VID.
 10. The networkingcomponent of claim 9, wherein the VDP response comprises a VDPType-Length-Value (TLV) field comprising a PCP/VID (PV) field, andwherein the PV field comprises the PS field, the PCP field, and a VIDfield.
 11. The networking component of claim 10, wherein the PS fieldcomprises about one bit, the PCP field comprises about three bits, andthe VID field comprises about 12 bits.
 12. The networking component ofclaim 10, wherein the PCP field provides the PCP value used to determinethe default PCP value adopted to the VSI when the PS field is set. 13.The networking component of claim 10, wherein the PCP field specifiesthe PCP value that is combined and used with other information known tothe networking component to specify the default PCP value, and whereinthe VDP response is used to associate the VSI to an EVB bridge port. 14.The networking component of claim 13, wherein the PCP value specified bythe PCP field is combined with at least one of the following: a value ofthe PCP set by a virtual machine (VM) user and associated with the VSI,an identity of an application associated with media access control (MAC)frames inferred by a hypervisor of the networking component, and apriority value specified by a network-layer packet associated with theMAC frames.
 15. The networking component of claim 10, wherein the PCPfield comprises a value that identifies a service class (SC).
 16. Thenetworking component of claim 9, wherein the PCP value is a first PCPvalue, wherein the VDP response comprises both the PCP value and aservice class (SC) value used to compute a second PCP value, and whereinthe second PCP value is less than the first PCP value.
 17. Thenetworking component of claim 9, wherein the VDP response comprises aservice class (SC) Significant (SCS) field, a SC field, the PS field,and the PCP field, wherein the SCS field and the SC field provide a SCassociated with at least some of a media access control (MAC) framessent on the VSI.
 18. A method implemented by at least one networkcomponent, comprising: sending from a virtual station to an Edge VirtualBridging (EVB) bridge a virtual station interface (VSI) discovery andconfiguration protocol (VDP) request that comprises a first PriorityCode Point (PCP) field and a first PCP Significant (PS) field; receivingat the virtual station a VDP response from the EVB bridge in response tothe VSI VDP request, wherein the VDP associate response includes asecond PCP field and a second PS field set to indicate a defaultpriority value; and adopting the default priority value to a VSI,wherein a plurality of media access control (MAC) frames transported viathe VSI comprise the default priority value.
 19. The method of claim 18,wherein the second PS field is set to one to indicate a significantsecond PCP field is set to indicate the default priority value, andwherein the first PCP field and the first PS field indicate whether ornot the virtual station expects the EVB bridge to supply the significantsecond PCP field.